Cannot use Grok 4.20 due to reasoningEffort being sent always for responses wire format

[kzu]

Describe the bug

I'm setting the following envvars:

Set COPILOT_PROVIDER_TYPE=openai
Set COPILOT_PROVIDER_BASE_URL=https://api.x.ai/v1
Set COPILOT_MODEL=grok-4.20-non-reasoning
Set COPILOT_PROVIDER_WIRE_API=responses
Set COPILOT_PROVIDER_MAX_PROMPT_TOKENS=2000000
Set COPILOT_PROVIDER_API_KEY=***********

There seems to be no way to turn that parameter off entirely (or even customize as proposed at #2559).

Ideally there should be support for setting off (don't send the parameter at all) as well as custom values via COPILOT_MODEL_EFFORT envvar

NOTE: despite 4.20 and 4.1 being reasoning models, the parameter is still not supported. See https://docs.x.ai/developers/model-capabilities/text/reasoning#the-reasoning-parameter

Affected version

1.0.34

Steps to reproduce the behavior

Set the above variables so they are valid for xAI (in particular your API key).

Expected behavior

Requests succeed.

Additional context

No response

[kzu]

Uff, doesn't work either with 4.20-reasoning!

✗ 400 "Model grok-4.20-reasoning does not support parameter reasoningEffort."